As environmental improvement advances socially, parts and manufacturing methods of electronic devices to reduce toxic substances are called for. A press-fit pin is known, which is mounted in a printed substrate (hereinafter also referred to as a substrate) by a press-fit method (press-fit method). To fit a press-fit pin to a through hole of a substrate, the press-fit pin can be mounted in the substrate without using solder. However, a press-fit pin has a connection structure using press fitting, thus imposes a heavy load to a substrate or a through hole, and importance is placed on improvement in reliability of a substrate.
The followings are reference documents.    [Document 1] Japanese Laid-open Patent Publication No. 2005-353774, and    [Document 2] Japanese Laid-open Utility Model Publication No. 61-83079.